Coating control apparatus



July 11, 1967 J. 5. CROWE 3,330,482

COATING CONTROL APPARATUS Filed May 10. 1963 2 $heets-$heet 1 BY flag;

July 11, 1967 J. s. CROWE 3,330,482

COATING CONTROL APPARATUS Filed May 10, 1963 2 Sheets-Sheet 2 i Z214 45g 1% t if /4 INVENTOR.

57/11/144 (Rad/f BY W M United States Patent Filed May 10, 1963, Ser.No. 279,424 9 Claims. (Cl. 239-74) The present invention relates to amethod of and apparatus for measuring the amount of coating beingapplied to a substrate material. More particularly, the inventionrelates to a volumetric system for monitoring the amount of coatingconsumption and thereby providing a running indication of the thicknessof the coating as it is being applied to the substrate material from apressurized supply line and while the coating is still in the wet orliquid state.

The industrial uses of coatings of all types are virtually endless, and,in the packaging industry alone, the use of coatings on various plastic,fiber and metal materials for either decorative, protective or adhesionpurposes is a growing field. Such coating materials as natural andsynthetic resins, paints, varnishes, waxes, sealant-s, adhesives andcertain metals, such as solder, are customarily applied as a film to asubstrate material. Common methods of applying these film coatings tothe selected substrate material are spraying, immersing, or by passingthe substrate material, either as a continuous web or in sheet form,over an applicator roll which carries the coating in a wet or liquidstate.

Whether the coating is applied as a protective film over the entiresurface of an article or sheet or merely as narrow strips of solder oradhesive to the marginal edges of a substrate web, it is generally ofprime importance that the uniformity of coating deposit be carefullycontrolled. This is so because, in addition to the necessity ofdepositing an adequate but not excess thickness to assure goodperformance, it is equally important to avoid excessive coatingthickness in order to keep waste of the normally expensive coating to aminimum.

In the past, time-consuming and rather tedious methods have beenemployed in measuring and controlling coating weight and thickness. Acommonly used test requires a waiting period until the coating has driedto a semi-wet or solid state, after which a test sample is subjected todestructive testing to determine the coating weight. Such spot checksystems are obviously slow and, accordingly, have motivated thedevelopment of more efiicient devices whereby periodic inspection can beaccomplished as the coating is continuously applied and without marringor destroying the coating by direct contact. The prior art discloses,and there are commercially available, several such devices, all of whichwork on such principles as optics, radiation, electrical charge,thermoelectrics or the like.

Many of the available devices have distinct limitations in that they areapplicable only to particular types of coatings or carrier materials.This is because the operational principles inherent in many of theseprior art systems are dependent on the nature of either the surfacebeing coated or the coating material itself, or both. Optical systems,for example, are applicable with acceptable accuracy only in situationswhere the light conductivity of coating and reflective characteristic ofthe coated surface are determinable parameters. More versatile systemsare available, of course, but usually they are rather sophisticateddevices which are extremely costly to install and require a certaindegree of excellence in operation and maintenance. Many of thesedevices, although capable of highly accurate and reliable performance inthe laboratory, have proven generally unsatisfactary in the practicalenvironment of the produc- 3,330,482 Patented July 11, 1967 tion linewhere the variables of temperature, vibration, lighting, dirtaccumulation, human judgment, and other factors are less easilycontrolled.

There is still a great need in the industry for a system of coatingconsumption control which is not only insusceptible to adverse shopconditions but which is also simple and inexpensive in construction,installation, operation and maintenance. The present invention fillsthis need in the industry by providing a volumetric system whichaccurately and directly measures the amount of coating being applied toa substrate material, from a pressurized supply line. In its basic form,the system comprises a test or measuring chamber which is connected intothe coating supply line and which is provided with a predeterminedamount of coating material that is maintained at a pressuresubstantially the same as the pressure in the coating supply line. Whenit is desired to measure the coating consumption, the coating applicatoris temporarily disconnected from the main supply line and is temporarilyconnected to the test chamber, so that the coating material in the testchamber is utilized in the coating operation for a predetermined timeinterval. The change in volume of the coating material in the testchamber is measured and related to the quantity of substrate materialcoated during the time interval to establish the consumption rate interms of volume of coating consumed per unit, per unit area, or per unitlength, as the case may be. The consumption rate is then compared to astandard or desired rate and a running correction is effected based onthe deviation from the standard for the selected time interval. In itspreferred form, the test chamber comprises a graduated sight glass whichmakes possible visual measurement of the change of volume of the coatingmaterial therein.

It is therefore an object of the present invention to provide anapparatus for rapidly and efiiciently measuring the amount of coatingbeing applied to a substrate material, which apparatus is simple inconstruction, operation and maintenance.

Another object of the invention is to provide an apparatus of thecharacter described which does not interfere with the speed of operationor result in loss of production and which is not destructive of eitherthe coating or the substrate material.

A further object of the invention is to provide an apparatus whichperiodically measures the amount of liquid coating being applied to aselected quantity of substrate material to permit timely determinationand control of the coating consumption.

A still further object of this invention is to provide a method ofrapidly and efliciently measuring the amount of liquid coating beingapplied to a substrate material, which method embraces simple mechanicalprinciples and which neither interferes with the continuous coatingoperation nor is destructive of the coating or substrate material.

Yet another object is to provide a method and apparatus for measuringand controlling coating consumption in a closed pressurized coatingsystem, which apparatus is an integral part of the pressurized system soas to measure accurately and directly the volume of coating materialbeing consumed without interfering with the continuous operation of thecoating system.

Still another object is to provide such a method and apparatus whereinthe weight of coating material being consumed can be directly measured.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

Referring to the drawings:

FIG. 1 is an elevational view, partly in section, of the apparatus usedin performing the objects of the present method invention, showing thevalve positions when the normal spraying operation is taking place andwith the coating material in the test chamber, here shown as a sightglass, at the low level which is reached at the end of the previous testcycle;

FIG. 2 i a view similar to FIG. 1, showing the valve positions after thesight glass has been filled with coating material to a predeterminedlevel, preparatory to the next test cycle;

FIG. 3 is a view similar to FIGS. 1 and 2, showing the valve positionsduring a test cycle; and

FIG. 4 is an elevational view corresponding to FIG. 3, of a modifiedform of the apparatus.

As a preferred or exemplary embodiment of the invention, FIGS. 1 through3 illustrate a volumetric coating control apparatus comprising a upplyline containing a pressurized liquid coating material C such as a resin,paint, varnish, wax, sealant, adhesive or a metal, such as solder or thelike. The coating material C is pressurized by a pump P which is incommunication with a reservoir (not shown) for the material to supplycoating material C to the line 10 under a predetermined pressure. Thesupply line 10 and a compressed air line 11 are connected to a materialapplicator such as a spray head 12 having an atomizing nozzle 14 whichfunctions to spray the coating material C onto a surface to be coated,such as the interior 16 of a tubular can body 18. The spray head 12 maybe of a type that is disclosed in the US. Patent 2,103,270, Murch,issued Dec. 28, 1937, which discloses a can spraying machine that couldbe used with the present coating control apparatus. In such a machine,the spray head operates intermittently to spray successive cans whichare automatically presented to it. The present volumetric coatingcontrol apparatus, however, can be used in continuous as well assuccessive coating operations.

A valve 19 comprising a casing 20 and a plug 21 rotatably mountedtherein is disposed in the supply line 10, and a conduit 22 is connectedat one end to the valve casing 20 and at the other end to the housing 24of a conventional, commercially available, pressure balancing or relayvalve 26. A flexible diaphragm 27 is mounted within the valve housing 24and one side thereof is in communication with the valve 19 via theconduit 22. The valve stem 28 is disposed on the other side of thediaphragm 27 and is provided with a flat head 29 which is secured to thediaphragm 27 and with an enlarged spherical portion 30 which is locatedadjacent one end of an orifice 32 in the housing 24. The orifice 32connects the other side of the diaphragm 27 with an air line 34containing air under a predetermined pressure which is greater than thatin the supply line 10. The valve stem 28 extends through the orifice 32and beyond the pherical portion 30 into a recess 35 in a plug 36 whichis threaded into or otherwise attached to the valve housing 24.

With the valve plug 21 in the position shown in FIG. 3, the pressure ofthe coating material C in the supply line 10 is transmitted by theconduit 22 to the one side of the diaphragm 27 in the pressure balancingvalve 26, while the other side of the diaphragm 27 is exposed to airpressure in a chamber 40 which is positioned adjacent thereto. When thecoating material pressure on the one side of the diaphragm 27 is equalto or less than the air pressure in the chamber 40, the sphericalportion 30 of the valve stem 28 occupies the position shown in FIG. 1,wherein the spherical portion 30 engages the conical seat 39 to seal theorifice 32 and prevent air under pressure from passing therethrough tothe chamber 40 and the adjacent side of the diaphragm 2'7.

When the coating material pressure exceeds the air pressure in thechamber 40, the diaphragm 27 is flexed (to the left as seen in FIG. 1),thus resulting in movement of the spherical stem portion 30 away fromthe conical seat 39. Pressurized air from the line 34 then passesthrough the orifice 32 into the chamber 40 until the air pressure on theadjacent side of the diaphragm 27 again equals the pressure of thecoating material C on the other side thereof, whereupon the sphericalportion 30 moves into engagement with the conical seat 39 to seal theorifice 32. It will be seen, therefore, that the function of thepressure balancing or relay valve 26 is to maintain the air on one sideof the diaphragm 27 at substantially the same pressure as that of thecoating material in the supply line 10. For a supply line pressure of 40p.s.i., for example, the pressure balancing valve has been found tofunction properly when air in the line 34 is at a pressure of 50 to 60p.s.i.

A second conduit 41 transmits the air under the same pressure as thepressure in the supply line 10 from the pressure balancing valve 26 to apneumatic valve 42 which comprises a casing 44 and a plug 46 rotatablymounted therein. A venting aperture 48 is provided in the casing 44 fora purpose to be described hereinafter, and the rate of venting iscontrolled by a bleeder valve 49 which may be operated manually orautomatically. In axial alignment with the conduit 41 and on theopposite side of the valve casing 44, there is disposed a third conduit52 which connects the valve 42 with the upper end of a test chamberwhich in this preferred form of the invention comprises a sight glass54. The sight glas 54 is provided with a transparent section 55 havinggraduations 56 thereon. A fourth conduit 58 is connected at one end tothe bottom end of the sight glass 54 and at the other end to the coatingsupply line 10.

During normal operation of the spray head 12, the coating material C ispumped from the reservoir (not shown) to the supply line 10 and is thentransmitted by the supply line '10 through the valve 19 and to the sprayhead 12. The valve plug 21 is in the position shown to in FIGS. 1 and 2to allow uninhibited flow of the coating material C through the supplyline 10, while preventing flow from the supply line 10 to the conduit 22leading to the pressure balancing valve 26. Since the conduit 58 isconnected directly into the supply line 10, the coating material C inthe supply line 10 is in communication with the graduated sight glass54. The valve 46 is positioned as shown in FIG. 2 so that the pressurein the sight glass 54 is the same as the pressure in the supply line 10,and as a result, the coating material C does not flow into the sightglass 54, but remains at the lowest level produced 'by the previous testcycle.

In order to reset the system for the next measuring operation, thecomponents are all set as shown in FIG. 1, thus, the valve 42 andbleeder valve 49 are manipulated to reduce the pressure in the sightglass 54. As shown, this is accomplished by positioning the valve plug46, whereby the pressurized air from the conduit 41 is cut off and theconduit 52 is brought into communication with the venting aperture 48,and by opening the bleeder valve 49. The bleeder valve 49 controls therate of venting and thus the rate at which the coating material C risesin the sight glass. When the coating material C reaches a predeterminedlevel 60 (see FIG. 2) in the sight glass, the bleeder valve 49 is closedand the coating material will no longer rise in the sight glass, owingto the remaining air pressure in the upper portion thereof.

FIG. 2 illustrates the volumetric coating control apparatus after thecoating material has risen to the predetermined level 60 in the sightglass 54 and before the measuring and testing of the coating consumptiontakes place. The valve plug 46 is now positioned to prevent the escapeof air through the venting aperture 48 and to establish communicationbetween conduits 41 and 52. At this time, the valve plug 21 is still inthe same position as that shown in FIG. 1, whereby coating materialpasses via the supply line 10 from the pump P through the valve 19, andto the spray head 12. It has been found that there is no tendency forthe level of the coating material in the sight glass to change to anyappreciable extent during this phase of the coating operation, since thepressure is equal on both ends of the column of coating material in thesight glass 54 and in the conduit 58. The pressure is equal on both endsof the coating material column because the valves 46 is set to preventthe air at the top end of the sight glass from escaping and escapethrough the balancing valve 26 is impossible.

When it is desired to measure the amount of coating material beingconsumed, the valve plug 21 is rotated to the position shown in FIG. 3,whereby the flow of coating material C from the pump P is cut off fromthe spray head 12 and the coating material pressure in the supply lineis re-established in the conduit 22. This causes the pressure balancingvalve 26 to maintain air in the air conduit 41 at the same pressure asthat of the coating material in the supply line 10, and because thispressure is transmitted through the conduit 52 to the sight glass, thecoating material C in the sight glass is under the same pressure a thatin the supply line 10. The pressure in the sight glass 54 immediatelyforces the coating material therein and in the conduit 58 into thesupply line 10, and to the spray head 12 to be used for the coatingoperation, without interruption of the coating machine whic-h embodiesthe spray head 12, so that the coating material C flows out of the sightglass 54, as seen in FIG. 3.

At the end of a predetermined time interval, or, alternatively, at theend of a predetermined number of coating cycles of the spray head -12,the valve plug 21 is rotated to the position shown in FIGS. 1 and 2,thereby establishing communication between the pump P and the spray head12. The coating material in the sight glass is now at its lowest level62 (see FIG. 1) which is lower than the initial level 60, and thedifference between these levels is an indication of the volume ofcoating material C consumed during the test cycle. This volume may bedirectly indicated by providing volumetric graduations 56 on thetransparent portion 55 of the sight glass 54. The volumetricconsumption, when related to the number of cans 1 8 coated during thepredetermined time interval or to a predetermined number of can coatingoperations can then be reduced to average weight (or thickness, byfurther computation) of coating applied to the interior surface 16 ofeach can, and can be compared to a standand or desired weight orthickness to determine if a correction in the consumption rate isrequired. The consumption rate may be corrected, if necessary, in theconventional manner by mechanical adjustment of the spray :gun 12 or bychanging the pressure of the coating material in the supply line 10.

FIG. 4 illustrates a modified form of the present invention, whereinthere is no valve 19 provided between the supply line 10 and the conduit22, with the result that there is constant communication therebetween.Instead, a valve 64 is provided at the juncture of the supply line 10and the conduit 58, the valve 64 comprising a casing 66 and a plug 68rotatably mounted therein. In FIG. 4, the plug 68 is positioned to cutoff the coating material from the pump P and to connect the conduit 58with the spray head 12. This position of the valve plug 68 correspondsto the active measuring phase of the coating operation disclosed in FIG.3, wherein the valve plug 21 similarly cuts off the flow from the pumpP.

During other phases of the coating operation, the valve plug 68 isrotated 90 in a clockwise direction from the position shown in FIG. 4,to connect the supply line 10 to the spray head 12 and to the conduit58. With the valve plug 68 in this position, the valve 44 and bleedervalve 58 are turned to the positions indicated in FIG. 1 to permit thecoating material C to rise in the sight glass 54 to the level 60. Exceptfor this modification in substitution of valve 64 for the valve 19, theapparatus of FIG. 4 is identical is construction and operation to thatshown in FIGS. 1 through 3.

While the coating control apparatus disclosed herein has been describedwith respect to individual and manual operation of the rotary andbleeder valves, it will be apparent that the valves may be connected bya suitable control system so as to function automatically atpredetermined times. Also, a control system may be provided toautomatically record the consumption as indicated by the graduated sightglass and correct it when there is a deviation from the standard ordesired consumption. For many coating operations, such an averagecoating determination taken at predetermined time intervals periodicallythroughout the course of the day has proven more than adequate toeffectively control coating quality and avoid excessive waste.

It will be readily seen that the principles of the invention are notlimited to the constructions disclosed in the drawings, and variousother modifications may be made without departing from these principles.For example, each of the valves 19, 26, 42 and '64 may be of anysuitable type or construction which is capable of functioning in thesame manner as the construction disclosed herein. Similarly, varioustypes of suitable volumetric indicators could be substituted for thegraduated sight glass 54.

In addition, while the present invention has been described primarily inconnection with a type of coating machine wherein individual cans arecoated sequentially,

it will be understood that it is equally suited for web coating,individual sheet coating, compound lining, or any other type of coatingor spraying operation where coating consumption per unit time is capableof volumetric determination and the applied material is maintained underpressure. If desired, a gravimetric rather than volumetric determinationcould be made of the amount of coating material drained from the sightglass during the selected testing interval. This could be accomplished,for

example, by suspending the sight glass from a balance in any suitablemanner and weighing it at the beginning and at the end of a testinterval to measure the weight rather than the volume of coatingmaterial consumed.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various other changes may be made in the form,construction and arrangement of the parts without departing from thespirit and scope of the invention or sacrificing all of its materialadvantages, the form hereinbefore described being merely a preferredembodiment thereof.

I claim:

1. Apparatus for measuring the volume of coating being applied to asubstrate material during a predetermined test interval, comprisingmeans for continuously supplying said coating at a predeterminedsubstantially constant pressure, means connected to said supplying meansfor directing said coating onto said substrate material, a test chamberconnected to said supplying means and containing therein a predeterminedvolume of coating from said supplying means, pressure balancing meanscommunicating with one end of said test chamber and said supplying meansfor supplying air to the coating in said test chamber at a pressure thesame as that of the coating in said supplying means, valve means fordisconnecting said supplying means and said directing means during saidtest interval, and simultaneously allowing said coating in saidreservoir to flow under said pre-determined pressure to said directingmeans during said test interval.

2. The apparatus of claim 1 wherein said valve means is disposed betweensaid supplying means and said pressure balancing means, and wherein saidvalve means is operative to connect said supplying means and saidpressure balancing means during said test interval to equalize thepressure of said air supplied by said pressure balancing means to saidtest chamber and the pressure of said coating material in said supplyline.

3. The apparatus of claim 1 wherein said pressure balancing means isconnected directly to said supplying means to receive the coatingpressure therefrom, and wherein said valve means is disposed betweensaid supplying means and the other end of said test chamber.

4. The apparatus of claim 1 wherein means are provided for selectivelypreventing the passage of air from 7 said pressure balancing means tosaid one end of the test chamber and for simultaneously venting the airin said test chamber.

5. Apparatus for determining the amount of coating material beingapplied to a substrate material during a test interval comprising asupply line for conveying said coating material from a supply sourceunder pressure, a material applicator on one end of said supply line, atest chamber, a coating material conduit connecting said supply line andsaid test chamber, a pressure balancing valve, an air line supplyingsaid balancing valve with compressed air at a pressure higher than thepressure of said coating material in said supply line, an air conduitfor conveying exhaust air from said balancing valve to said testchamber, said balancing valve operative to communicate with said supplyline and equalize the pressure of said air exhausted into said airconduit, with the pressure of the coating material in said supply line,a bleeder valve for selectively decreasing the air pressure in said testchamber to a pressure below that of said coating material in said supplyline to allow a pre-determined amount of said material to flow from saidsupply line, through said coating material conduit and into said chamberand valve means to selectively withdraw said material from said chamberor said supply source.

6. The apparatus defined in claim 5 wherein bleeder valve is operativeto selectively vent said test chamber to the atmosphere.

7. The apparatus defined in claim 5 wherein said material applicator isa spray gun.

8. The apparatus defined in claim 5 wherein said means to selectivelywithdraw said coating material from said supply line includes a valvewhich is operative to put said balancing valve selectively in or out ofcommunication with said supply line.

9. The apparatus defined in claim 5 wherein said means to selectivelywithdraw said coating material from said chamber is a valve operative toprevent communication of said material conduit and said supply linewhile permitting communication between said supply line and saidmaterial applicator or alternatively to prevent communication of saidsupply line with said applicator while per mitting communication betweensaid test chamber and said applicator.

References Cited UNITED STATES PATENTS 2,826,067 3/1958 Braunlich 73-1683,000,207 9/1961 Goife 73223 X 3,172,779 3/1965 Warshaw et al. 118-93,179,291 4/1965 Umbach et al 73l68 ALFRED L. LEAVITI, Primary Examiner.

E. B. LIPSCOMB, Assistant Examiner.

1. APPARATUS FOR MEASURING THE VOLUME OF COATING BEING APPLIED TO ASUBSTRATE MATERIAL DURING A PREDETERMINED TEST INTERVAL, COMPRISINGMEANS FOR CONTINUOUSLY SUPPLYING SAID COATING AT A PREDETERMINEDSUBSTANTIALLY CONSTANT PRESSURE, MEANS CONNECTED TO SAID SUPPLYING MEANSFOR DIRECTING SAID COATING ONTO SAID SUBSTRATE MATERIAL, A TEST CHAMBERCONNECTED TO SAID SUPPLYING MEANS AND CONTAINING THEREIN A PREDETERMINEDVOLUME OF COATING FROM SAID SUPPLYING MEANS, PRESSURE BALANCING MEANSCOMMUNICATING WITH ONE END OF SAID TEST CHAMBER AND SAID SUPPLYING MEANSFOR SUPPLYING AIR TO THE COATING IN SAID TEST CHAMBER AT A PRESSURE THESAME AS THAT OF THE COATING IN SAID SUPPLYING MEANS, VALVE MEANS FORDISCONNECTING SAID SUPPLYING MEANS AND SAID DIRECTING MEANS DURING SAIDTEST INTERVAL, AND SIMULTANEOUSLY ALLOWING SAID COATING IN SAIDRESERVOIR TO FLOW UNDER SAID PRE-DETERMINED PRESSURE TO SAID DIRECTINGMEANS DURING SAID TEST INTERVAL.
 5. APPARATUS FOR DETERMINING THE AMOUNTOF COATING MATERIAL BEING APPLIED TO A SUBSTRATE MATERIAL DURING A TESTINTERVAL COMPRISING A SUPPLY LINE FOR CONVEYING SAID COATING MATERIALFROM A SUPPLY SOURCE UNDER PRESSURE, A MATERIAL APPLICATOR ON ONE END OFSAID SUPPLY LINE, A TEST CHAMBER, A COATING MATERIAL CONDUIT CONNECTINGSAID SUPPLY LINE AND SAID TEST CHAMBER, A PRESSURE BALANCING VALVE, ANAIR LINE SUPPLYING SAID BALANCING VALVE WITH COMPRESSED AIR AT APRESSURE HIGHER THAN THE PRESSURE OF SAID COATING MATERIAL IN SAIDSUPPLY LINE, AN AIR CONDUIT FOR CONVEYING EXHAUST AIR FROM SAIDBALANCING VALVE TO SAID TEST CHAMBER, SAID BALANCING VALVE OPERATIVE TOCOMMUNICATE WITH SAID SUPPLY LINE AND EQUALIZE THE PRESSURE OF SAID AIREXHAUSTED INTO SAID AIR CONDUIT, WITH THE PRESSURE OF THE COATINGMATERIAL IN SAID SUPPLY LINE, A BLEEDER VALVE FOR SELECTIVELY DECREASINGTHE AIR PRESSURE IN SAID TEST CHAMBER TO A PRESSURE BELOW THAT OF SAIDCOATING MATERIAL IN SAID SUPPLY LINE TO ALLOW A PRE-DETERMINED AMOUNT OFSAID MATERIAL TO FLOW FROM SAID SUPPLY LINE, THROUGH SAID COATINGMATERIAL CONDUIT AND INTO SAID CHAMBER AND VALVE MEANS TO SELECTIVELYWITHDRAW SAID MATERIAL FROM SAID CHAMBER OR SAID SUPPLY SOURCE.
 7. THEAPPARATUS DEFINED IN CLAIM 5 WHEREIN SAID MATERIAL APPLICATOR IS A SPRAYGUN.